In traditional measurement systems, there are typically a finite number of fixed measurement devices, all known to and controlled by the measurement system. Generally such measurement devices are specifically configured and deployed for use by the measurement system at or as near as is practicable to a point at which measurement data is to be collected. When a set of measurements is to be made the system typically will download or otherwise configure each of these devices via whatever communication medium is provided, e.g., a measurement bus such as an IEEE-488 BUS, a local area network (LAN) connection, a serial link, or the like. The measurements are then made on command, periodically, or perhaps based on a time schedule. Depending on the sophistication of the devices, these measurements may be made by the device relatively independently from the rest of the measurement system. For example, a scheduled or periodic data collection based on an internal device clock, perhaps synchronized to other clocks in the system may be made. Alternatively, devices may require an active command from the system for each measurement. The results typically are then delivered to the rest of the measurement system via the communication medium. Such measurement systems also typically include one or more processors or computers that execute control and analysis software for the measurement system.
One of the key features of these existing systems is that the identity and location of each measurement device is known. Typically this information forms a basis for initiating control and for associating any resulting data with real world parameters being measured. Accordingly, the device identity, however represented, is often a pseudonym for the location of measurement and the resultant measure. Typically users of existing measurement systems know what instruments are available, what the instruments' locations are, how to access the instruments explicitly, and when data will be returned.
These traditional technologies for building a measurement or control system typically employ a rack of equipment connected to a computer or other processing device via an IEEE-488 interface or LAN. In such a system a user knows exactly which instruments are available. Typically a user writes a program or otherwise sets up a schedule to make measurements. In short, in existing measurement systems a user knows what is being tested, all the instruments available when the measurements are going to made, and when data will be returned. Thus, existing measurement systems are relatively closed.
IEEE Standard 1451.2 formalizes something that has been present to a greater or lesser degree in at least some existing classes of measurement instruments. IEEE 1451.2 provides standard units of measurement, how often measurements can be taken, the accuracy of the measurement, limits of the measurements, how to correct for nonlinearities in the measurement device, and the like which are contained within an electronic data sheet that a computer or interface may read. Thus, an IEEE 1451.2 compliant instrument returns not only a reading, but also sufficient information, metadata, as to how to interpret the reading including units of measure, the instrument accuracy, and the like. IEEE 1451.2 is the standard that addresses how to specify that metadata.
IEEE standard 1451.2 has allowed some freedom with respect to use of measurement devices by providing an orderly and explicit representation of some aspects of measurements, such as units, standardized names of variables, and the like, to be resident in existing measurement devices supporting this standard. This allows supporting measurement devices to be “self-describing” with the result that an anonymous device may be able to report its properties or measurements without reference to its location or identity. However, existing systems, even those with IEEE 1451.2 compliant devices, still typically require explicit representation of the identity of devices. Moreover, existing systems are generally unable to provide meaningful analysis of data without accurate reference to its location.
Existing mobile measuring techniques typically employ transporting equipment to a known location to take measurements at known and/or scheduled times. In existing measurement systems a user wants to know some fact about the world or a particular environment at a particular place and time. To gather this fact the user places an instrument at that place so it can take a measurement at the desired time, or the user sends an instrument to that place to take a measurement at that time.